1. Field of the Invention
The present invention relates to methods and related devices for forming a passageway in a heart wall and delivering a stent therein to supply oxygenated blood flow to vascular structure from a chamber of the heart. For example, the methods and related devices preferably place a stent in the left ventricular heart wall in order to establish a supply of blood from the left ventricle to the coronary artery at a point distal a partial or total occlusion of the artery.
2. Background of the Related Art
A prevalent form of heart failure involves the build-up of plaque on walls of various vascular structure, such as, for example, the coronary artery. The plaque that builds up on the walls can form either a partial or total occlusion in the artery. Such an occlusion may either limit or completely block blood flow through the artery, which typically enters through the aortic valve from the left ventricle. Because the coronary artery supplies blood to the various blood vessels within the muscle forming the heart wall, limiting or blocking of the blood flow through the coronary artery can result in damage to the heart muscle, such as, for example, necrosis. Necrotic tissue can lead to reduced cardiac function by diminishing the pumping capacity of the heart. In some instances, the diminished capacity of the heart can lead to heart attack.
Various techniques have been developed to treat this type of heart condition. For example, a surgical technique, referred to as coronary artery bypass grafting (CABG), involves removing a vein or portion thereof from the patient, usually from the femoral vein, and grafting the vein so as to connect portions of the coronary artery upstream and downstream of the occlusion. Thus, the blood flow is directed around the occlusion and through the vein graft so that the oxygenated blood can be delivered to the vessels in the heart wall. CABG generally is performed as an open surgery resulting in relatively long recovery times. Patients also often experience a large amount of discomfort resulting from harvesting of the veins to be used in CABG. Furthermore, the veins that are grafted to the coronary artery have a limited useful life.
Coronary angioplasty represents another form of treatment of arteries having occlusions that can be performed as an alternative to bypass surgery. In this technique, a balloon catheter is inserted percutaneously into the coronary artery. Once the catheter has been inserted such that the balloon is adjacent the occlusion being treated, the balloon is inflated to dilate the artery in the location of the occlusion. Often this technique involves inflating and deflating the balloon repeatedly to establish the desired dilation of the artery. This technique may include placing a stent in a collinear manner in the artery at the location of the occlusion to maintain the proper dilation of the artery. Delivery of the stent can be accomplished by removing the dilation balloon catheter and then inserting a balloon carrying the stent. A multiple balloon stent delivery catheter may dilate the artery and place the stent in a single insertion of the catheter into the patient.
Another technique that has been used to bypass a partial or total occlusion of the artery includes implanting a stent, or otherwise creating a flow passage, in the myocardial wall between the left ventricle and coronary artery at a position downstream of the occlusion. In this technique, a portion of the blood pumped from the left ventricle flows directly into the coronary artery.